y t i C n a o b r u e T m l l a e n w i C o a f t f P n a u e s t 9 o k a k 8 s a e a M n L g e g r o a a P a l d l d l o e i F e 4 c 6 C s V i S c n n a o r F y n n a a S e 0 t C t 8 u 1 d B n d a e s r R 0 G m 8 4 1 6 a 4 i 6 n l l i a y W a s u T 0 4 - I APPENDIX 1: REGIONAL MAP MAP APPENDIX 1:REGIONAL 9 3 n 6 a 6 m g n i K s e l d A R I Z O e N A e N C A L I F O R N I A � Regional Map. The green area is the approximate area of Grand Canyon National Park. GLOSSARY absolute age – a numeric unit that is assigned to signify the age of something angular unconformity – a gap in the geologic record formed where horizontal layers lie directly on top of layers that have been tilted anticline – an upward fold in rock layers (in the shape of an “A”), where the youngest layers are usually on the top of the fold, and the oldest layers are in the center of the fold asthenosphere – the soft solid layer of mantle that lies below the lithosphere and drives the movement of tectonic plates atom – the smallest particle of an element, composed of protons, neutrons and elec- trons atomic number – the total number of protons in an atom atomic weight – the total of the masses of the protons and neutrons in an element basalt – a dark, fine-grained, extrusive igneous rock composed of low silica, iron-rich minerals base level – the elevation of a stream’s mouth or outlet; the lowest elevation that the stream can cut down to butte – a landscape feature with a flat top that is at least as tall as it is wide, generally narrower than a mesa calcrete – (see caliche) caliche – a hard, white substance composed of primarily calcium carbonate; it forms on the surface of rocks or as a soil layer chemical weathering – the process by which the chemical composition of a rock is broken down and minerals that in the rock are altered chert – a hard substance composed of very fine (micro-crystalline) quartz crystals, made of pure silica (SiO2) that may form irregular shaped nodules and blobs in a rock continental crust – the thick, buoyant crustal material that underlies continents, which 94 causes the land to float higher on the mantle and sit above sea level convergent plate boundary – where two plates slowly collide, one plate usually sub- ducts beneath the other causing volcanoes to form on the over-riding plate and earth- quakes to occur where the plates are in contact and on the subducting plate; when two continents collide, there may be no subduction zone convection – the transport and circulation of energy due to differences in density; it is caused by the circulation of hot, less dense material rising while cold, denser material sinks core – the center portion of the Earth, which is composed of heavy nickel and iron material cross bedding – the angled, layered appearance in a sedimentary rock, formed as wind or water deposits particles in ripples or sand dunes crust – the Earth’s outermost layer, which is mainly composed of compounds of oxygen and silica (silicates) crystalline – a description of metamorphosed rock and/or intrusive igneous rock with visible mineral crystals daughter isotope – the product of radioactive decay of an unstable, radioactive parent isotope delta – the fan-shaped sedimentary feature formed where a river meets the ocean or some large body of water, and the sediment carried by the river begins to settle out and deposit; named after the shape of the delta symbol. dike – a vertical intrusive igneous feature formed when magma cuts across or is squeezed into rock discharge – the volume of water that a river or stream carries in a given time; usually measured in cubic feet per second (cfs) disconformity – a gap in the geologic record between sedimentary layers, formed when there is a period of erosion or no deposition, but there is no tilting of the layers divergent plate boundary – where two plates rip apart and move in opposite directions, usually accompanied by volcanoes and small, shallow earthquakes earthquake – the energy released due to built up strain energy along a fault element – the most basic form of matter, which has distinct, identifying physical and 95 chemical properties eolian – sediment transported and deposited by wind, such as sand dunes erosion – the transport of rock material by forces such as water and wind that takes place in conjunction with and subsequent to weathering estuary - a body of water near a shoreline that is joined with the ocean where fresh and saline water mix extrusive – (volcanic) igneous rocks that form as lava pours out onto the Earth’s surface and quickly cools evaporite – a mineral that was once dissolved in water, but as the water evaporated the mineral was precipitated out fault – a crack in rocks with movement parallel to the surface of the crack flint –dark grey chert colored by impurities fluvial– river or stream depositional environment fold – a bend in rocks that were once horizontal and flat foliation – the parallel alignment of platy or prismatic minerals in metamorphic rocks formation – a mappable rock layer of a distinct and recognizable rock type(s) that can be distinguished from the rocks above and below it; the fundamental stratigraphic unit fossil – any mineralized remains, traces, or remnants of once living organisms fracture – (see joint) geology – the study of the Earth and the surface and sub-surface processes that shape it geomorphology – the study of the geologic processes that create landscapes on the Earth’s surface and shape geologic landforms glauconite – a mineral in clay or shale that often has a greenish color gneiss – a highly metamorphosed rock with foliation of light and dark bands of minerals gradient – the slope of a stream or change in elevation of the channel over some dis- tance 96 granite – a light, usually pink colored, intrusive igneous rock composed of large, high- silica minerals groundwater – water that flows through channels and pore spaces within rocks beneath the Earth’s surface group – several stratigraphic formations that represent similar depositional environ- ments in geologic time gypsum – a soft evaporite mineral usually colorless, yellow, white, grey, or pink half-life – the amount of time it takes for half of a parent isotope to decay to form a daughter isotope headward erosion – the process of erosion from the steepest parts of river channels as a river cuts back towards its headwaters hydrology – the study of the movement of water hypothesis – a testable scientific idea that is an attempt to explain the observations of some phenomenon may have occurred ice wedging – the physical weathering process that occurs when water freezes in cracks and the ice expands, gradually widening the cracks in the rock igneous rock – cooled and hardened Earth material that was once partly or completely molten inner core – the center-most, solid portion of the Earth, composed of the dense iron and nickel-rich minerals intertidal zone – a low-lying area near sea level that is sometimes submerged and other times exposed due to tidal or sea level changes intrusive – (plutonic) igneous rocks that cool and harden slowly beneath the Earth’s surface isotope –one of many forms of an element that has the same number of protons, but a different number of neutrons, giving it a different atomic weight; one element can have several isotopes and some may be radioactive jasper – red chert colored by impurities joint – a crack in a rock with little or no upward or downward movement in directions 97 parallel to the crack; the rocks simply move apart perpendicular to the cracked surface lava – igneous, molten rock that is erupted onto the Earth surface limestone – a sedimentary rock composed mainly of calcium carbonate (CaCO3), or “lime,” that has chemically precipitated from seawater or composed of the hard parts of some marine organisms; the lime settles on the sea floor, eventually forming a hardened rock lithosphere – the Earth’s solid outer layer made up of both the crust and the uppermost part of the mantle; it is divided into tectonic plates mantle – the layer between the core and the crust of the Earth made up of compounds of oxygen and silica (silicates) rich in iron and magnesium magma – igneous, molten rock that exists below the Earth’s surface mass movement – the physical weathering process that occurs when huge portions of rock are washed away or fall mechanical weathering – (see physical weathering) member – the stratigraphic division of a rock unit in a formation mesa – a large, flat-topped hill that is wider than its height; generally wider than a butte mesosphere – the lower, solid layer of the mantle that lies between the asthenosphere and the outer core metamorphic rock – sedimentary, igneous, or other metamorphic rocks that have been re-crystallized by heat and/or pressure mineral – a substance that occurs naturally, is inorganic, and is composed of different elements combined to make a crystalline solid monocline – a fold that is neither an anticline nor a syncline, with only one folded side, which looks similar to a ramp mud crack – a sedimentary feature formed when mud is exposed to air, dries and cracks into pieces nonconformity – a gap in the geologic record formed where sedimentary layers lie directly on top of intrusive igneous or metamorphic rock normal fault – a fault that forms as the upper block drops down relative to the lower 98 block, usually as a result of pulling or extensional geologic forces, such as occurs at divergent plate boundaries ocean crust – the thin, heavy crustal material that exists beneath the oceans outer core – the